Supplemental change for druntime pull 522.
fix Issue 10498 - `__traits(compiles, ...)` affect program behaviour
fix Issue 10558 - Assertion failure on struct.c:741

A template instance on temlpate argument may not have yet valid `Dsymbol::ident`, so should use `Dsymbol::getIdent()` for hash calculation.
fix Issue 10499 - retro is no longer CTFE-able
Merge pull request #2318 from 9rnsr/fix10499

[REG2.064a] Issue 10499 - retro is no longer CTFE-able
Merge pull request #2314 from 9rnsr/fix10558

[REG2.064a] Issue 10558 - Assertion failure on struct.c:741
Merge pull request #2310 from denis-sh/supplemental-change-for-druntime-pull-522

Supplemental change for druntime pull 522.
Merge pull request #2280 from 9rnsr/fix10498

[REG2.061] Issue 10498 - `__traits(compiles, ...)` affect program behaviour